1. Technical Field
The present invention relates to a hydrogen generating apparatus and to a fuel cell power generation system.
2. Description of the Related Art
A fuel cell is an apparatus that converts the chemical energies of fuel (hydrogen, LNG, LPG, methanol, etc.) and air directly into electricity and heat, by means of electrochemical reactions. In contrast to conventional power generation techniques, which employ the processes of burning fuel, generating vapor, driving turbines, and driving power generators, the utilization of fuel cells does not entail combustion processes or driving apparatus. As such, the fuel cell is the result of new technology for generating power that offers high efficiency and few environmental problems.
FIG. 1 is a diagram illustrating the operating principle of a fuel cell.
Referring to FIG. 1, a fuel cell 100 may include a fuel electrode 110 as an anode and an air electrode 130 as a cathode. The fuel electrode 110 receives molecular hydrogen (H2), which is dissociated into hydrogen ions (H+) and electrons (e−). The hydrogen ions move past a membrane 120 towards the air electrode 130. This membrane 120 corresponds to an electrolyte layer. The electrons move through an external circuit 140 to generate an electric current. The hydrogen ions and the electrons combine with the oxygen in the air at the air electrode 130 to generate water. The following Reaction Scheme 1 represents the chemical reactions described above.

In short, the fuel cell can function as a battery, as the electrons dissociated from the fuel electrode 110 generate a current that passes through the external circuit. Such a fuel cell 100 is a relatively pollution-free power source, because it does not produce any polluting emissions such as SOx, NOx, etc., and produces only little amounts of carbon dioxide. The fuel cell may also offer several other advantages, such as low noise and little vibration, etc.
In order for the fuel cell 100 to generate electrons at the fuel electrode 110, a hydrogen generating apparatus may be needed, which modifies a regular fuel containing hydrogen atoms into a gas having a high hydrogen content, as required by the fuel cell 100.
A hydrogen storage tank can be used, as a commonly known substitute for the hydrogen generating apparatus, but the tank apparatus occupies a large volume and has to be kept with special care. In order for the fuel cell to suitably accommodate the demands in current portable electronic devices (e.g. cell phones, laptops, etc.) for high-capacity power supply apparatus, the fuel cell needs to have a small volume while providing high performance.
FIG. 2 is a perspective view schematically illustrating a hydrogen generating apparatus supplying hydrogen to the fuel cell 100 illustrated in FIG. 1. The hydrogen generating apparatus 200 may include an electrolyte bath 210, first electrodes 220, second electrodes 230, and a control unit 240. For better understanding and more convenient explanation, the following descriptions will assume that the first electrodes 220 are of made magnesium (Mg) and the second electrodes 230 are made of stainless steel.
The electrolyte bath 210 may contain an electrolyte solution 215. The hydrogen generating apparatus 200 may use the electrolyte solution 215 to generate hydrogen gas. The electrolyte bath 210 may further include a hydrogen outlet 250, through which hydrogen may be discharged, and a gas-liquid separation membrane 260 placed at one end of the hydrogen outlet 250 connected with the electrolyte bath 210 that permits the discharge of hydrogen while preventing the discharge of the electrolyte solution 215.
The electrolyte bath 210 can contain the first electrodes 220 and the second electrodes 230. The first and second electrodes 220, 230 may be completely or partially immersed in the electrolyte solution 215.
FIG. 3A is a cross sectional view of the hydrogen generating apparatus illustrated in FIG. 2 when the hydrogen outlet faces a direction opposite the direction of gravity, while FIG. 3B is a cross sectional view of the hydrogen generating apparatus illustrated in FIG. 2 when the hydrogen outlet faces the same direction as the direction of gravity.
Referring to FIGS. 3A and 3B, changing the orientation of the hydrogen generating apparatus 200, in which the positions of the first electrodes and second electrodes 220, 230 are fixed, can lead to a difference in reaction area between the electrolyte solution 215 and the electrodes, and hence to a difference in the amount of hydrogen generated. In FIG. 3B, an area of each electrode corresponding to “A” may not contact the electrolyte solution 215. Thus, the amount of hydrogen generated in a given period of time may differ, making it difficult to supply a constant amount of hydrogen to the fuel cell 100.
A method of resolving this difficulty can be to supply the electrolyte solution in the lower portions to the upper portions using a pump. However, this would require the use of a separate pump and valves, and thus would run counter to efforts for providing compact sizes.